The aim of this paper was to investigate the levels of maternal serum placental protein13 (PP13), beta human chorionic gonadotropin (β-hCG) and progesterone in the prediction of miscarriages in threatened miscarriages. A total of 110 patients with a gestational age < 14 weeks were included in the study. A total of 42 patients were allocated as the study group (threatened miscarriage) and 68 patients were allocated as controls. A total of six miscarriages were observed in the study group. β-hCG levels were significantly lower in the group with threatened miscarriage when compared with controls (p = 0.018). There was no statistically significant difference in regard to progesterone and PP13 levels occurred between two groups (p = 0.653 and p = 0.062, respectively). Following receiver operating characteristic (ROC) analysis, the β-hCG parameter was found useful in differentiating miscarriages from the threatened miscarriage group (p = 0.031). PP13 and progesterone parameters in predicting miscarriages were not found as statistically significant (p = 0.084 and p = 0.914, respectively). This study suggests that β-hCG measurements could be useful in predicting spontaneous miscarriage in women presenting with threatened miscarriage. Even though PP13 seems unfeasible to be used as a predictive marker for miscarriage, factors affecting PP13 levels should be considered along with the need for comprehensive studies including larger patient populations.